[PATCH] mm: i386 sh sh64 ready for split ptlock

Use pte_offset_map_lock, instead of pte_offset_map (or inappropriate
pte_offset_kernel) and mm-wide page_table_lock, in sundry arch places.

The i386 vm86 mark_screen_rdonly: yes, there was and is an assumption that the
screen fits inside the one page table, as indeed it does.

The sh __do_page_fault: which handles both kernel faults (without lock) and
user mm faults (locked - though it set_pte without locking before).

The sh64 flush_cache_range and helpers: which wrongly thought callers held
page_table_lock before (only its tlb_start_vma did, and no longer does so);
moved the flush loop down, and adjusted the large versus small range decision
to consider a range which spans page tables as large.

Signed-off-by: Hugh Dickins <hugh@veritas.com>
Acked-by: Paul Mundt <lethal@linux-sh.org>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

1 files changed, 23 insertions, 17 deletions

diff --git a/arch/sh/mm/fault.c b/arch/sh/mm/fault.c
index 7abba2161da6..775f86cd3fe8 100644
--- a/arch/sh/mm/fault.c
+++ b/arch/sh/mm/fault.c
@@ -194,10 +194,13 @@ asmlinkage int __do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
                                unsigned long address)
 {
         unsigned long addrmax = P4SEG;
-        pgd_t *dir;
+        pgd_t *pgd;
         pmd_t *pmd;
         pte_t *pte;
         pte_t entry;
+        struct mm_struct *mm;
+        spinlock_t *ptl;
+        int ret = 1;
 
 #ifdef CONFIG_SH_KGDB
         if (kgdb_nofault && kgdb_bus_err_hook)
@@ -208,28 +211,28 @@ asmlinkage int __do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
         addrmax = P4SEG_STORE_QUE + 0x04000000;
 #endif
 
-        if (address >= P3SEG && address < addrmax)
-                dir = pgd_offset_k(address);
-        else if (address >= TASK_SIZE)
+        if (address >= P3SEG && address < addrmax) {
+                pgd = pgd_offset_k(address);
+                mm = NULL;
+        } else if (address >= TASK_SIZE)
                 return 1;
-        else if (!current->mm)
+        else if (!(mm = current->mm))
                 return 1;
         else
-                dir = pgd_offset(current->mm, address);
+                pgd = pgd_offset(mm, address);
 
-        pmd = pmd_offset(dir, address);
-        if (pmd_none(*pmd))
-                return 1;
-        if (pmd_bad(*pmd)) {
-                pmd_ERROR(*pmd);
-                pmd_clear(pmd);
+        pmd = pmd_offset(pgd, address);
+        if (pmd_none_or_clear_bad(pmd))
                 return 1;
-        }
-        pte = pte_offset_kernel(pmd, address);
+        if (mm)
+                pte = pte_offset_map_lock(mm, pmd, address, &ptl);
+        else
+                pte = pte_offset_kernel(pmd, address);
+
         entry = *pte;
         if (pte_none(entry) || pte_not_present(entry)
             || (writeaccess && !pte_write(entry)))
-                return 1;
+                goto unlock;
 
         if (writeaccess)
                 entry = pte_mkdirty(entry);
@@ -251,8 +254,11 @@ asmlinkage int __do_page_fault(struct pt_regs *regs, unsigned long writeaccess,
 
         set_pte(pte, entry);
         update_mmu_cache(NULL, address, entry);
-
-        return 0;
+        ret = 0;
+unlock:
+        if (mm)
+                pte_unmap_unlock(pte, ptl);
+        return ret;
 }
 
 void flush_tlb_page(struct vm_area_struct *vma, unsigned long page)